1. Field of the Invention
The present invention relates to a laser treatment apparatus for treating an affected part by irradiating it with a laser beam for treatment.
2. Description of Related Art
In laser treatment apparatus which is represented by a YAG laser used in the field of ophthalmology, the focal position of a laser beam for treatment is made to shift for an aiming light in an optical axis direction when an operation of incising posterior capsule for after cataract treatment or iris for glaucoma treatment is carried out, in order to reduce the effect by the impact of the treatment laser beam to an intraocular lens and to raise the efficiency of incising. The YAG laser is constructed to concentrate the energy of the laser beam on the focal point, whereby to cut off the tissue irradiated by the laser beam.
FIG. 7 shows the case that the focal position of the treatment laser beam is shifted in the optical axis, in which the focal position of an aiming light is located at the position F1. In this case, there are two ways to shift the focal position of the YAG laser beam, namely, one way is to shift the focal position to a back side (an eye fundus side) as indicated by a position F2 and another is to shift the same to a front side (an operator side) as indicated by a position F3.
The way to shift the focal position to the back side up to the position F2 is performed when an object which requires not to be injured by the YAG laser beam, such as an intraocular lens, exists on the front side. In the after cataract, it is necessary to incise opaque posterior capsule by the treatment YAG laser beam. However, intraocular lens has been inserted on the operator side, and the focal position of the YAG laser beam is shifted to the back side in order to prevent the laser beam from injuring the lens in error.
The way to shift the focal position to the front side up to the position F3 is performed when an object which requires not to be injured by the YAG laser beam exists on the back side.
In the above laser treatment, the setting of the focal shift position of the treatment laser beam is often changed according to patient eye cases and for each person.
However, in the case that the laser treatment apparatus is used for a patient's eye different from an eye that was treated with the identical apparatus at the last time, in particular, in the case that the identical apparatus is used by plural operators, the confirmation or reset of the focal shift position for the laser beam are often forgotten, and the laser irradiation might be carried out using the focal shift position set at the last time use (when the other operator used, and other cases). Therefore, the purposed treatment effect may not be obtained. There is also the fear that the intraocular lens may be injured in error in the operation of the after cataract, when the focal position of the YAG laser beam is located at the position corresponding to that of the aiming light or on the front side.
To avoid the above problem, under present circumstances, the means such as specification in instruction manuals and attachment of attention labels to the apparatus are taken. However, those are not always reliable.